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目的:探讨雌激素受体β(estrogen receptorβ,ERβ)的表达与乳腺癌他莫昔芬(tamoxifen,TAM)内分泌治疗耐药的相关性及其机制。方法:以前期构建的ERα/ERβ不同表达的人乳腺癌MCF-7细胞株[M/HK(阴性对照)、M/siα(ERαlow/ERβhigh)、M/siβ(ERαhigh/ERβlow)细胞]为研究对象,MTT法评估乳腺癌细胞对TAM的耐药性;用半定量RT-PCR法检测细胞中耐药相关基因MDR1、TOPOⅡ、LRP和GST-π的mRNA表达水平,用Western blotting法检测细胞中耐药相关信号通路MAPK、PI3K/Akt的p-ERK、p-Akt蛋白表达水平。结果:与对照组MCF-7细胞相比,MCF-7细胞中的ERβ高表达可促进高浓度TAM(1、5、10μmol/L)对MCF-7细胞增殖的抑制作用[(45.788±1.641)%vs(24.288±1.170)%,(57.899±1.583)%vs(31.499±1.978)%,(59.853±1.648)%vs(38.039±1.482)%;均P<0.05)],该抑制作用与TAM浓度呈剂量依赖性。ERβ高表达可显著抑制MCF-7细胞耐药基因MDR1、TOPOⅡ、LRP的mRNA表达水平(0.431±0.032 vs 0.932±0.083,0.234±0.008 vs 0.391±0.002,0.47±0.028 vs 0.586±0.036;均P<0.05);可显著下调Akt和ERK蛋白的磷酸化水平(0.224±0.006 vs 0.437±0.007,0.367±0.015 vs 0.756±0.039;均P<0.05)。结论:ERβ表达水平可影响乳腺癌细胞MCF-7对TAM的耐药性,该作用机制可能与耐药基因的表达及PI3K/AKT、MAPK信号通路激活有关。
Objective: To investigate the relationship between the expression of estrogen receptorβ (ERβ) and the endocrine resistance of breast cancer tamoxifen (TAM) and its mechanism. Methods: The human breast cancer MCF-7 cell line [M / HK (negative control), M / siα (ERαlow / ERβhigh) and M / siβ (ERαhigh / ERβlow) The MTT assay was used to assess the resistance of breast cancer cells to TAM. The mRNA expression levels of multidrug resistance-related genes MDR1, TOPOⅡ, LRP and GST-π were detected by semi-quantitative RT-PCR and Western blotting Drug-resistant signaling pathway MAPK, PI3K / Akt p-ERK, p-Akt protein expression levels. Results: Compared with MCF-7 cells in MCF-7 cells, high expression of ERβ in MCF-7 cells could promote the proliferation of MCF-7 cells with high concentration of TAM (1,5,10 μmol / L) [(45.788 ± 1.641) % vs (24.288 ± 1.170)%, (57.899 ± 1.583)% vs (31.499 ± 1.978)%, (59.853 ± 1.648)% vs (38.039 ± 1.482)%, all P <0.05) In a dose-dependent manner. ERβ overexpression significantly inhibited the mRNA expression of MDR1, TOPOⅡ and LRP in MCF-7 cells (0.431 ± 0.032 vs 0.932 ± 0.083,0.234 ± 0.008 vs 0.391 ± 0.002,0.47 ± 0.028 vs 0.586 ± 0.036, all P < 0.05). The phosphorylation levels of Akt and ERK were significantly down-regulated (0.224 ± 0.006 vs 0.437 ± 0.007, 0.367 ± 0.015 vs 0.756 ± 0.039; all P <0.05). CONCLUSION: The expression level of ERβ can affect the resistance of breast cancer cell MCF-7 to TAM. The mechanism may be related to the expression of drug resistance gene and the activation of PI3K / AKT and MAPK signaling pathway.